Nightly compiler error: cannot relate bound region

[ngsankha]

Came across this error while building on the nightly compiler on Travis: https://travis-ci.org/troposphere/boron/jobs/145311447

Relevant log lines:

error: internal compiler error: ../src/librustc/infer/region_inference/mod.rs:734: cannot relate bound region: '_#0r <= ReEarlyBound(TypeSpace, 0, 'r)
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
thread 'rustc' panicked at 'Box<Any>', ../src/librustc_errors/lib.rs:580
note: Run with `RUST_BACKTRACE=1` for a backtrace.

[TimNN]

This is probably #34839 and should be fixed in the next nightly.

[jonas-schievink]

Fixed in current nightly

[alexcrichton]

Yay!